RESUMEN
Metal nanostructures have attractive electrical and thermal properties as well as structural stability, and are important for applications in flexible conductors. In this study, we have developed a method to fabricate and control novel complex platinum nanostructures with accordion-like profile using atomic layer deposition on lithographically patterned polymer templates. The template removal process results in unique structural transformation of the nanostructure profile, which has been studied and modeled. Using different template duty cycles and aspect ratios, we have demonstrated a wide variety of cross-sectional profiles from wavy geometry to pipe array patterns. These complex thin metal nanostructures can find applications in flexible/stretchable electronics, photonics and nanofluidics.
RESUMEN
Atomic layer deposition (ALD) is investigated as a process to produce inorganic metallic bio-adhesive coatings on cellulosic fiber substrates. The atomic layer deposition technique is known to be capable of forming highly conformal and uniform inorganic thin film coatings on a variety of complex surfaces, and this work presents an initial investigation of ALD on porous substrate materials to produce high-precision biocompatible titanium oxynitride coatings. X-ray photoelectron spectroscopy (XPS) confirmed TiNOx composition, and transmission electron microscopy (TEM) analysis showed the coatings to be uniform and conformal on the fiber surfaces. Biocompatibility of the modified structures was determined as a function of coating layer thickness by fluorescent live/dead staining of human adipose-derived adult stem cells (hADSC) at 6, 12 and 24 h. Cell adhesion showed that thin TiNOx coatings yielded the highest number of cells after 24 h with a sample coated with a 20 A coating having approximately 28.4 +/- 3.50 ng DNA. By altering the thickness of the deposited film, it was possible to control the amount of cells adhered to the samples. This work demonstrates the potential of low temperature ALD as a surface modification technique to produce biocompatible cellulose and other implant materials.
Asunto(s)
Celulosa/química , Materiales Biocompatibles Revestidos/química , Nanopartículas/química , Titanio/química , Tejido Adiposo/citología , Adhesión Celular , ADN/química , Humanos , Microscopía Electrónica de Transmisión , Nanotecnología/métodos , Espectrometría por Rayos X/métodos , Células Madre/citología , Propiedades de Superficie , Temperatura , Factores de TiempoRESUMEN
OBJECTIVE: Residents frequently use humor and slang at the expense of patients on the clinical wards. We studied how medical students react to and interpret the "appropriateness" of derogatory and cynical humor and slang in a clinical setting. DESIGN: Semistructured, in-depth interviews. SETTING: Informal meeting spaces. PARTICIPANTS: Thirty-three medical students. MEASUREMENTS: Qualitative content analysis of interview transcriptions. MAIN RESULTS: Students' descriptions of the humorous stories and their responses reveal that students are able to take the perspective of both outsiders and insiders in the medical culture. Students' responses to these stories show that they can identify the outsider's perspective both by seeing themselves in the outsider's role and by identifying with patients. Students can also see the insider's perspective, in that they identify with residents' frustrations and disappointments and therefore try to explain why residents use this kind of humor. Their participation in the humor and slang--often with reservations--further reveals their ability to identify with the perspective of an insider. CONCLUSIONS: Medical students describe a number of conflicting reactions to hospital humor that may enhance and exacerbate tensions that are already an inevitable part of training for many students. This phenomenon requires greater attention by medical educators.
Asunto(s)
Actitud del Personal de Salud , Internado y Residencia , Estudiantes de Medicina/psicología , Terminología como Asunto , Conducta Verbal , Ingenio y Humor como Asunto , Adulto , Ética Médica , Femenino , Procesos de Grupo , Hospitales de Enseñanza , Humanos , Entrevistas como Asunto , MasculinoRESUMEN
Hydrogen atoms can selectively eliminate strained bonds that form during the growth of amorphous silicon films. By periodically interrupting the growth and exposing the grown material to hydrogen, the film composition can be varied continuously from a non-equilibrium amorphous structure to that of a crystalline solid. Furthermore, by tuning the hydrogen exposure it is possible to discriminate between Si-Si bonds formed on different substrates, thereby allowing substrate-selective growth. The evolution of the film structure during hydrogen exposure is directly observed by scanning tunneling microscopy, and a model describing the role of hydrogen is presented.